The five-time major champion said that a family doctor had been prescribing her a drug called Mildronate (also known as Meldonium) since 2006. "I had several health issues going on at the time," she explained. "I was getting sick very often, I had a deficiency of magnesium, irregular EKG results, family history of diabetes -- and that’s one of the medications, along with several others that I had received."

Sharapova made a point to mention that she had been legally taking the medicine for the past decade, as Meldonium did not become banned by the World Anti-Doping Agency until this year. Sharapova insisted that she was not made aware of the change.

"I made a huge mistake," she admitted. "I let my fans down. I let the sport down that I've been playing since the age of 4, that I love so deeply."

According to Sharapova, she was notified about failing the drug test in a letter from the International Tennis Foundation on March 2, but she has yet to find out what the penalty will be.

"I know that with this I face consequences and I don't want to end my career this way," she said. "I really hope that I will be given another chance to play this game."

As one of tennis' biggest stars, Sharapova has been the world's highest-paid female athlete for 11 years straight. According to Forbes, she pulled in $29.5 million in 2015 -- $6.7 million from winning matches and $23 million in endorsements. Some of her biggest endorsers include Porsche and Cole Haan.